Snap action electric switch

ABSTRACT

A snap action switch for alternating and direct current, improved by a solid support for the movable contact means in combination with a substantial distance between the stationary contacts. For longer life a robust spring mechanism is insulated against gas, arising from the arc.

United States Patent Spaderna 51 May 23, 1972 [54] SNAP ACTION ELECTRICSWITCH [72] Inventor: Conan Henry Spaderna, 8 Edmund St.,

Longmeadow, Mass. 01028 [22] Filed: Feb. 9, 1971 [21] Appl. No.: 113,957

52 U.S. Cl ..200/67 8 511 int. Cl. ..H01h 13/28 58 Field of Search..200/67 R, 67 B, 67 D, 67 A [56] References Cited UNITED STATES PATENTS1,870,127 8/1932 Lewis .....200/67 B 2,455,927 12/ 1948 Grady ..200/67 BPrimary Examiner-David Smith, Jr.

[ ABSTRACT A snap action switch for alternating and direct current,improved by a solid support for the movable contact means in combinationwith a substantial distance between the stationary contacts. For longerlife a robust spring mechanism is insulated against gas, arising fromthe are.

10 Chins, 5 Drawing figures Patented May 23, 1972 3,665,131

E9. 4 g 5 INVENTOR m/nHfoadu/na,

SNAP ACTION ELECTRIC SWITCH Generally snap switches have a springmechanism enclosed in the arc chamber and thus exposed to the hot gasesof the electric arc, which leads to earlier breakage than necessary. Itsenclosure in the arc chamber restricts the size of the spring mechanismand hence the stored energy, available for the snap movement of themovable contact. As the snap energy is small, the movable contact has tobe light and therefore breaks easily.

To overcome these drawbacks, the invention uses springs outside aninsulating housing base, which thus shields the springs from heat andgases of the arc. A housing top above the housing base has a slot forthe actuating lever to stick out. The housing base is shaped with acylindrical cavity, to receive an insulating wheel. This wheel issubstantially concentric with the cylindrical upper face of the housingbase and is adapted to rotate in the housing, when turned by the lever,e.g. by a transverse shaft, pivoted in the housing top.

At least one pair of stationary contacts projects from the cylindricalbase face. One or more movable contact means are so attached to thewheel that contact can be made across neighboring stationary contacts byturning the wheel. One or more spring mechanisms of the dead center typeare attached outside of the housing base with their fixed ends to thehousing top and with their center to an eccentric trunnion of the wheel.Stops are provided for halting the wheel rotation in closed or openpositions of the switch.

The invention is shown in the drawing. However, it is to be understoodthat this invention is not limited to the details shown, but may embodymodifications within its scope. In the drawing:

FIG. 1 is an end view ofa switch embodying this invention;

FIG. 2 is a side view of the section on line A-AAAA-A through FIG. 1looking from the right of FIG.1;

FIG. 3 is a bottom view thereof, seen from below of FIG.2;

FIG. 4 is an end view of a modified element in a section, marked by lineC-C of FIG.5, seen from left of FIG.5, and

FIG. 5 is a side view thereof in a section on line BB, seen from theright of FIG.4.

1n the switch shown in FIGS. 1,2 and 3, a housing top 1 has brackets 11and 12, formed in one piece with an oblong metal strap 15. This strap ispierced by holes 13 for screw attachment to a wall box, not shown, andtapped holes 14 for screw fastening of a not shown conventional lid;with household equipment on rollers a nook can house the switch.Fastened to the housing top is a housing base 2, made of plastic, e.g.Nylon. It comprises in the present embodiment two upright posts 16 thatmake easier the assembly of housing base and top, after the wheel 3 hasbeen mounted. Small knobs 17 on the posts snap into opposite holes ofthe brackets 11 and 12.

A protective casing 18 of fiber or metal may be slipped over the wholelength of the housing base tightly like a sheath, but it is open on top,except for narrow retaining ledges 19. For floor polishers, vacuumcleaners etc. the metal strap may have different shapes, such as a ringsegment to be screwed unto a round handle, while the switch rests insidethe cut open handle.

In FIGS. 1,2, and 3 two movable contacts 21 and 22 can open or closecircuits across stationary contact bars 8,, S S and S resting insertedin the housing base 2. The stationary contacts end in eight terminalswith running numbers 23 30, each having a suitable binding screw 32. InFIG. 2 the movable contacts are in positions 21 and 22 when the lever 31takes its right hand position 31. The same contact means hold positions21' and 22 when the left hand position 31' of the lever, shown indash-dot lines, is reached. The movable contacts are well embedded inthe wheel 3, which is shaped for this purpose with a peripheral groove33 and insertion niches 34. The wheel center is pivoted and secured byits metal shaft 35. This may be also achieved by two plastic trunnions,molded unto the wheel in its center. The wheel itself may be made ofplastic or fiber; it is pivoted in and guided between the brackets 11and 12.

The spring mechanisms are: 36 on the left hand side of FIG.1 and 37 onthe right hand side. To avoid crowding of the drawing with lines,mechanism 37 is shown by the spring symbol, a rectangular withdiagonals, which symbol is also used on one side of FIG.3 and on the twosides of FIGSA and 5. Each spring mechanism has two springs: 36 has thesprings 38 and 38', while 37 has the springs 39 and 39'. These springsare hooked at one end to lugs 44 of the metal strap 15, at their 7 otherend to an eccentric trunnion 40 of the wheel 3.

If the wheel is turned by putting the lever 31 from one end of a strapslot 41 in FIG.2 to the other slot end, the trunnion 40 describes a how42. This bow path has to be above the upper contour 43 of the housingbase 2, as free movement of the trunnions must be insured.

It can be best seen in FIG.2 how the switch operates. If lever 31 isthrown from its position 31 into position 31, the trunnion 40 swings inits bow path 42 through dead center to a position 40'. The heavy pull,formerly exerted by the spring 38, is now coming from the elongatedspring 38, while the spring 38' is relaxed. Thus two stable positions ofthe switch exist, which are defined as well as by the places where thelever rests, as by the extreme locations of the trunnion. If the leveris taking its position 31", then the movable contact 22 is not touchingany stationary contact and, being embedded in the groove 33, (F IG.1) itcannot touch any metal at all. At the same time the movable contactbridges the stationary contact bars S and S.,. If the lever stays at 31,one movable contact holds an off-position 21, while the other makescontact between the stationary contact bars S and S;,.

In FIGS. 4 and 5 all parts carry the same characters as theircorresponding parts in FIGS. 1 3, yet, the number of movable contactmeans is raised to three (FIG.5); the number of stationary contact barsstays four, but each bar has only one terminal(FIG.4). Chosen positions51 57 of the movable contacts are marked by arrows on the wheel rim inFIGS. Although three movable contacts 52, 54 and 56 are shown here, oneor two may be left out,if not needed. With lever 31 upright, only thecircuit of the stationary contacts 29 and 30 is closed. The wheel 3 istemporarily locked in that position by a spring loaded bolt 58, seateddeep in the wheel 3 and reaching into a shallow hole, made for thispurpose in the bracket 12. By pushing further the level 31, one canovercome this stop. At 59 and 60, more holes provide stops for furtherlocations of lever 31; the stop 60 will halt the wheel after a short,clockwise travel in such a manner that the movable contact, formerly inposition 52, will reach the location 51, which is all around insulated.The center contact travels from 54 to 53, closing a circuit between Sand S after opening a circuit between S and S Meanwhile, the contactfrom position 56 bridges the contacts S and S.,.

Readily, the same location of the movable contacts and of the stops 5860 can be applied to the switch of FIGS. 1 3. It follows that a switchcan be made for a variety of circuits, whose handling otherwise wouldrequire several switches. One movable contact in the center, or two ormore movable contacts may be employed, using the same housing top andbase, as well as the same spring mechanisms. This rich versatility is anew and desirable feature of the present invention, as the same toolscan be used to make a variety of switches.

The second embodiment of the invention features some structuraldifferent against the first one. The upright posts 16 of the housingbase 2 are replaced in FIGS by two metallic end walls 16' of the housingtop 1- casing 18' assembly. As shown in FIG.4, the casing is slightlyoffset at the height 43 of the plastic housing base 2', to hold thelatter firmly in place. Because the base 2 is smaller than the base 2,the former is less expensive to mold. However, the assembly requiresears 61 on top of the end walls 61', which ears are screwed to the strap15 by screws 62, after the wheel 3 has been set in its place. Two leafsprings 63 are fastened to the end walls 16, to press downward on thewheel top with their roughened underside; thus those springs brake thesnap momentum just before it reaches a stop, such as one end of the slot41 in FIG. 5. The

wheel is made slimmer in its top section, see 31 in F162, as it has topass through the strap slot. Therefore stronger braking takes place whenthe wheel is turning up its broader part under the leaf springs 63,shown on the far side in F104. By that frictional braking suddenvibration and harsh impact with the stop are kept away from the wheel.

The snapwheel switch, as described, is useful for small electric motorsin altering the sense of turning by reversing one A.C. phase, or inspeed changes by switching to a different combination of field coils.Both methods are known, but the invention offers possibilities of highervoltage and wattage, as the movable contact will stop often beyond thestationary contacts, opposite cooler housing parts. There the hot,ionized air cools and de-ionizes, forestalling restrikes of the are.

This feature prolongates the life of the switch in other applications,too, even where only small currents are being switched.

in F162 a jumper 64, of the same metal as all the contacts, ties theterminals 23 and 25; by this means the switch may be converted into atwoway switch. Either the first circuit is closed by the movable contact21, or the other circuit may be closed by the movable contact 22 in itslocation 22'. The switch, shown here, has eight terminals, while theconventional twoway switches offer only two terminals for loads, and onefor the source. For this reason they were misnamed threeway" switches.

in F105 one or both spring mechanisms might be arranged upside down withthe trunnion 40" between the center 35 and top 31 of the wheel, and lugs44 disposed on the endwalls 16 of the housing top 1'. Yet, commonly atrunnion 40 is seated in the area between the bottom 54 and wheelcenter.

I claim:

1. In an electric switch for snap action, a housing having a topprovided with a slot, further having an insulating housing base shapedwith an inner cylindrical face; at least two spaced stationary electriccontacts projecting from the cylindrical face of the housing base; aninsulating wheel substantially concentric with said cylindrical face andbeing disposed for rotation in the housing and provided with anactuating lever projecting through the slot; at least one movablecontact means carried by the wheel for movement by it across thestationary contacts; at least one spring mechanism disposed outside thehousing base with a center and ends whereof the ends are fastened to thehousing top and the center is attached eccentrically to the wheel; andstops provided for the wheel to halt its rotation in open and closedpositions of the switch.

2. An electric switch as set forth in claim 1, wherein the ends of theslot in the housing top provide the stops for the wheel lever in bothdirections.

3. An electric switch as set forth in claim I, wherein the wheel isshaped with a peripheral groove and the movable contact means areattached inside the groove.

4. An electric switch as set forth in claim 1, wherein the housing topis further provided with at least one leaf spring pressing on the rim ofthe wheel; and wherein said rim is made wider where a halt under theleaf spring is intended to raise friction there.

5. An electric switch as set forth in claim 1, wherein a spring loadedstop bolt is further provided projecting from a flat wheel face; and acavity in an opposite wall of the housing is adapted to receive thebolt.

6v An electric switch as set forth in claim 1, wherein the housing topis formed into a bracket with spaced ledges and aligned holes in theledges; and wherein the wheel is provided in its center with atransverse shaft that is mounted in said holes for rotation.

7. An electric switch as set forth in claim 1, wherein the eccentrictrunnion is mounted between the center and the top of the wheel.

8. An electric switch as set forth in claim 1, wherein the eccentrictrunnion is mounted between the center and the bottom of the wheel.

9. An electric switch as set forth in claim 1, wherein the

1. In an electric switch for snap action, a housing having a topprovided with a slot, further having an insulating housing base shapedwith an inner cylindrical face; at least two spaced stationary electriccontacts projecting from the cylindrical face of the housing base; aninsulating wheel substantially concentric with said cylindrical face andbeing disposed for rotation in the housing and provided with anactuating lever projecting through the slot; at least one movablecontact means carried by the wheel for movement by it across thestationary contacts; at least one spring mechanism disposed outside thehousing base with a center and ends whereof the ends are fastened to thehousing top and the Center is attached eccentrically to the wheel; andstops provided for the wheel to halt its rotation in open and closedpositions of the switch.
 2. An electric switch as set forth in claim 1,wherein the ends of the slot in the housing top provide the stops forthe wheel lever in both directions.
 3. An electric switch as set forthin claim 1, wherein the wheel is shaped with a peripheral groove and themovable contact means are attached inside the groove.
 4. An electricswitch as set forth in claim 1, wherein the housing top is furtherprovided with at least one leaf spring pressing on the rim of the wheel;and wherein said rim is made wider where a halt under the leaf spring isintended to raise friction there.
 5. An electric switch as set forth inclaim 1, wherein a spring loaded stop bolt is further providedprojecting from a flat wheel face; and a cavity in an opposite wall ofthe housing is adapted to receive the bolt.
 6. An electric switch as setforth in claim 1, wherein the housing top is formed into a bracket withspaced ledges and aligned holes in the ledges; and wherein the wheel isprovided in its center with a transverse shaft that is mounted in saidholes for rotation.
 7. An electric switch as set forth in claim 1,wherein the eccentric trunnion is mounted between the center and the topof the wheel.
 8. An electric switch as set forth in claim 1, wherein theeccentric trunnion is mounted between the center and the bottom of thewheel.
 9. An electric switch as set forth in claim 1, wherein thehousing base contains two pairs of stationary contacts and wherein roomfor a jumper is provided to tie the neighboring contacts of each paircompleting two parallel circuits to be switched alternatively.
 10. Anelectric switch as set forth in claim 1, wherein the stationary contactsare formed into terminals at both ends to allow parallel circuits to beconnected.